Chemistry topic 2 - Titration and S1.3

Solute

Substance being dissolved

Solvent

liquid in which dispersion occurs

Solution

homogenous mixture of 2+ substances

Dilute

solution containing small amount of substance

Concentrated

Solution with large amount of solute

Concentration

amount (moles) of substance in a given volume of solvent

Titration

Technique used to determine the unknown concentration of a solution by reacting with a solution of a known concentration

Isotope

Atom of an element, same number of protons but different number of neutrons, only changes physical properties

Volatile

Easily evaporated at normal temperatures

Ionization

Neutral electrically charged atoms/molecules connected to electrically charged atoms (ions) through gaining or losing electrons

Mass spectrometry

Analytical technique used to determine molecular mass of a compound and individually helped to prove the existence of isotopes

Ion

An atom or molecule with a net electrical charge

5 stages of mass spectrometry

vaporization, ionisation, acceleration, deflection, detection

Continuous spectrum

Shows broad bands of electromagnetic radiation (emission) or shadow (absorption)

Emission line spectrum

contains only some discrete lines of electromagnetic radiation (emission)

Absorption line spectrum

or shadows (black lines superimposed on a continuous spectrum).

Hydrogen absorption/emission spectrum

If observed through a spectroscope each element gives a characteristic set of colours or lines, at fixed wavelengths.

First ionisation energy

Minimum required energy to remove an electron from an atom or a mole of electrons from a mole of atoms in its gaseous state

γ rays, x rays, UV, visible, IR, Microwaves, radiowaves - state 4 on left

left - high frequency, short wavelength, high energy, converge

Lyman series

Higher energy to n=1, viewed was UV radiation, highest energy transitions

Balmer series

Higher energies to n=2, visible light, medium energy transition

Paschen series

Higher energies to n=3 is IR, lowest energy transitions

Aufbau principle

When adding electrons to an atom, lowest energy levels are filled first

Pauli exclusion principle

Atomic orbital can only hold 2 electrons, and they must have opposite signs

Hunds rule

With degenerate orbitals, each orbital is filled with single electron before being doubly occupied (on bus)

Degenerate orbitals

Orbitals of the same energy

Strong nuclear force

Overcomes repulsion between positively charged protons, attracts subatomic particles such as protons and neutrons toward each other

Atomic radius

distance between nucleus and valence electrons

Convergence limit

frequency or wavelength that corresponds with ionisation

Successive ionisation energies

Energies required to remove more and more electrons from an ion that is becoming increasingly positive

He electron configuration

1s2

Ne electron configuration

1s2 2s2 2p6

Ar electron configuration

1s2 2s2 2p6 3s2 3p6

Kr electron configuration

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6

Xe electron configuration

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6

Heisenberg uncertainty principle

not possible to know location and velocity of very small electrons, only probability that they will be in electron clouds 90% of time

shielding

the reduction in electrostatic attraction between the positive nucleus and outer-shell electrons, caused by the repulsive forces of inner-shell (core) electrons